Cultivation of black soldier fly larvae in substrates containing antibiotics

Abstract

The use of antibiotics in agriculture to treat and prevent infectious diseases and to stimulate growth results in antibiotics accumulating in animal tissues and wastes. Further utilization of such animal waste causes an increase in antibiotic-resistant bacteria. One of the promising ways of manure processing leading to reduction of antibiotic concentrations and obtaining useful biomass from organic waste may be bioconversion with the help of insects, particularly black soldier flies (Hermetia illucens) ( Diptera: Stratiomyldae). It is important to know how the presence of antibiotics in the feeding substrate affects the insects and their characteristics for further utilization. The effect of adding the antibiotics ceftriaxone, coliflox, levofloxacin and their mixtures to feed substrates on the growth of black soldier fly larvae was studied. When ceftriaxone, coliflox and levofloxacin were given at a concentration of 1–100 mg/kg feed, an increase in mean larval weight was observed compared to the control group after 5 days of culturing. At antibiotic concentrations of 500–1000 mg/kg, this effect was compensated, presumably by the negative effect of the antibiotic on the microbiota of the insect digestive system. At antibiotic concentrations of 2000 mg/kg feed, growth of Hermetia illucens larvae was retarded. No effect of antibiotics on fatty acid composition, moisture and ash content of insects was found. The results indicate that the use of black soldier fly for the treatment of animal waste is feasible, but the likely negative effect on insect growth at high antibiotic concentrations should be considered.